1. Physicochemical properties of thermotolerant extracellular β-glucosidase from Talaromyces thermophilus and enzymatic synthesis of cello-oligosaccharides.
- Author
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Mallek-Fakhfakh H and Belghith H
- Subjects
- Enzyme Stability, Extracellular Space, Glycosylation, Hydrogen-Ion Concentration, Hydrolysis, Metals pharmacology, Molecular Weight, Polysaccharides metabolism, Solvents pharmacology, Substrate Specificity, Sugar Alcohols pharmacology, Talaromyces enzymology, Talaromyces physiology, beta-Glucosidase isolation & purification, Cellobiose chemical synthesis, Cellobiose chemistry, Talaromyces cytology, Temperature, beta-Glucosidase chemistry, beta-Glucosidase metabolism
- Abstract
A thermophilic fungus, Talaromyces thermophilus that produces a novel thermotolerant extra-cellular β-glucosidase (Bgl.tls), was isolated from Tunisian soil samples. The enzyme was purified from the culture filtrates of T. thermophilus grown on lactose using gel filtration, ion exchange chromatography and FPLC. The monomeric enzyme had a molecular mass of 116.0 kDa and a high specific activity of 1429 UI/mg. Bgl.tls exhibited optimal activity at pH 5.0 and 65 °C. It was also stable over a wide range of pH (4.0-10.0) and stable at 50 °C for 34 h. Bgl.tls retained about 80% of its initial activity after 1.0 hours of preincubation at 60 °C. The Km and Vmax values recorded for pNPG were 0.25 mM and 228.7 µmol min(-1), respectively. Bgl.tls was activated by Mn(2+), Mg(2+), Ca(2+) and Co(2+) but obviously inhibited by Fe(2+) and Cu(2+). It was able to hydrolyze a variety of aryl / alkyl -β-glucosides and disaccharides as well as (1 → 6) and (1 → 4)-β-glucosidic linkages and α-glycosidic substrates, thus providing evidence for its broad substrate specificity. The enzyme also displayed high hydrolytic and transglycosylation activities. Overall, this study is the first report on the purification and physicochemical properties of a β-glucosidase secreted by T. thermophilus. The cello-oligosaccharides synthesized by this enzyme within 2 h were mainly cellotriose, cellotetraose and cellopentaose identified by HPLC and ESI-MS techniques., (Copyright © 2015 Elsevier Ltd. All rights reserved.)
- Published
- 2016
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